Rabbits: They are adorable. They hop around, eat vegetation, and crinkle their noses in a heart-melting way. Full disclosure: I am personally a big fan. My parents’ suburban neighborhood has tons of rabbits, and whenever I see one I make sure to point at it and say, “Hey, look — a rabbit!” (I say this even if I’m alone.)
But there’s a dark side to rabbits. The multiply like … well, I’m not sure what an appropriate comparison here would be. But they breed a lot. Australians know this better than anyone. As Ben Goldfarb notes in a new article in Science, a small population of European rabbits was introduced to Australia “by an English settler as hunting fodder in 1859,” and shortly thereafter — whoops — there were 10 billion of them on the continent. This horde “contribut[ed] to extensive environmental damage and the extinction of some native species,” and has been a serious problem ever since.
Ironically, Australia’s viral progress began with a mortifying error. Government researchers were experimenting with the rabbit haemorrhagic disease virus (RHDV) on Wardang Island, off South Australia’s coast, when renegade flies picked up the pathogen and transported it to the mainland. Luckily, the containment failure became a smashing success: The virus eradicated an estimated 60% of Australia’s rabbits, acting with particular lethality in arid areas. The government officially released the disease in 1996.
As RHDV spread, researchers documented encouraging ecosystem changes. Native vegetation bounced back, and populations of large herbivores such as kangaroos increased.
Still, no one was quite certain how RHDV’s advance was affecting some groups of animals, including Australia’s small desert mammals. Several rodents, such as the dusky hopping mouse and the plains mouse, had nearly vanished during the rabbit takeover. So had the crest-tailed mulgara, a hamster-sized marsupial that preys on lizards and insects. Both the dusky hopping mouse and the plains mouse are considered vulnerable by the International Union for the Conservation of Nature (IUCN), and the mulgara is listed as endangered in South Australia.
The Conservation Biology study, which involved “pull[ing] together 45 years of mammal trapping surveys conducted by the state government, mining companies, and nongovernmental groups,” found that these and other species are in fact on the upswing, and that their bounce-backs seem to be traceable to the release of the virus.
Sure, the downside was many, many, many dead rabbits. But remember: It was the rabbits, not the Aussies, who started this war.